What causes electrical feedback?

Electrical feedback occurs when a portion of an output signal is fed back into the input of a system, creating a loop. This can happen in various electronic circuits, such as amplifiers, where it can enhance or stabilize performance. However, if the feedback is excessive or improperly managed, it can lead to unwanted oscillations or distortion, commonly known as feedback noise. In audio systems, for example, this often manifests as a loud screeching sound when a microphone picks up sound from a speaker it is connected to.